Answer:
66.9375
Step-by-step explanation:
from what you told me 4cm=21km
if you divide 21 by four, you get how many km is one cm. which is 5.25km
15 divided by 4 = 3.75
what we know is that 4 can go into 15 three whole times. so.. 21x3=63
now what we need to figure out is that .75
so, 75 is three quarters, so i divided 5.25 divided by 4 to get how much one quarter of a cm is in km. then i multipled that by three, giving me: 3.9375
63+3.9375= 66.9375
but you might have to round this i dont know if you do or not so thats the answer im giving
